This invention relates to conversion systems. It is particularly adapted for conversion systems making easy-open can ends and the like, although it will be understood that it could apply to presses manufacturing other types of parts.
Presses for converting ends for cans are known. Presses of this general type are available from the Minster Machine Company of Minster, Ohio. U.S. patent application Ser. No. 143,585, filed Jan. 13, 1988, and assigned to the present assignee, shows a general layout of a press for processing work pieces or shells into finished can ends. The disclousre of that application is hereby incorporated by reference herein.
The presses used for the manufacture of easy-open can ends generally comprise a press bed mounted on legs, which rest on the floor. Four columns or uprights or pillars are mounted on the press bed. The columns support a crown in which a main drive for the various press components is mounted. The columns also have slides or ways attached thereto for supporting a reciprocating ram. The ram carries upper tooling, which cooperates with lower tooling on the bed. The tooling defines a plurality of stations in which the shells are progressively converted into easy-open can ends. A conveyor carries the shells into and through the stations of the die tooling. The shells merely rest in openings in the conveyor. They are held in place by a vacuum box placed generally underneath the forward run of the conveyor at the area of the tooling.
While it is known to use a vacuum box to retain the shells on the conveyor, the load imposed by the vacuum box on the shells is, of course, transferred to the conveyor itself. Conventional conveyors are then subject to deflection under the influence of the vacuum box. This can cause loss of registration between the shells and the tooling, which in turn causes production of defective parts.